Well, today was my first experience with All Grain brewing. I loved every second of it, and I think I did pretty well overall (thanks in large part to this forum). I did have a couple minor issues, and I'm hoping for a little clarification on boil off rate and how it affects OG.

I ended up boiling off more than BeerSmith had predicted (about 1/2gallon more than expected). I also ended up overshooting my OG (target- 1.057, actual 1.064). Are these two things related?

I'm thinking (hoping) that boiling off eliminates H2O from the wort, but not sugars, unfermentables, etc., thereby raising the OG as water is lost to evaporation. Am I on track here? I just want to understand why I missed the OG so I can plan better next time. Thanks!